!!! 64-BIT BINARIES ARE UNOFFICAL !!! If you did not press the ABOUT menu item, you probably did not previously add 64-bit binaries with this graphical interface. The 64-bit binaries that you can add with this interface are an UNOFFICAL addition to TeX Live. They are created by Akira Kakuto, who also maintains most 32-bit binaries for TeX Live. Installing these 64-bit binaries will NOT change your searchpath to include them. Instead, a new command-prompt shortcut, titled 'TeX Live 64-bit' will be created which prefers the 64-bit binaries over the 32-bit ones. You can also configure your editor to prefer 64-bit, but that is up to you. Shortcut creation may fail on Windows 7. WARNING If the 64-bit binaries are not in step with the 32-bit ones, you might run into problems with format files. When an update involves a TeX compiler ([la]tex, pdf[la]tex, lua[la]tex, xe[la]tex) or metafont/metapost, it is best to also rerun this 64-bit installer. THIS IS YOUR OWN RESPONSIBILITY! Normal 32-bit operation should not be affected, but this also depends on your editor configuration. RE-SYNCING Another consideration is the actual set of 64-bit binaries which are installed. When installing or updating them, 64-bit binaries which do not have a corresponding 32-bit binary are automatically removed. Therefore, if you add or remove packages, you should also do a re-sync, or an update, which includes a re-sync. GHOSTSCRIPT You may need to also install a 64-bit ghostscript. An installer can be downloaded from https://mirror.ctan.org/systems/win32/TLW64/